NO ONE can have expected his views to have changed, but nor can they have expected the Pope to be quite so quick to register his opposition to President Bill Clinton's stand on abortion during his trip to the United States.

As the pontiff yesterday began his second day in Denver, Colorado, onlookers were still registering surprise at his decision to tackle his biggest gripe with the US leader, minutes after touching down.

He avoided using the a-word, but no one among the thousands gathered to greet him was in any doubt of his meaning when he urged Americans to 'guarantee the right to life'; Mr Clinton, an abortion-rights advocate, stood impassively beside him.

'In each man, woman and child, in every immigrant, in every native- born son or daughter, the ultimate test of your greatness is the way you treat every human being,' he said, 'especially the weakest and most defenceless.' Perhaps the US's greatest cause was to 'guarantee the right to life and protect the human person . . . If you want equal justice for all, and true freedom and lasting peace, then, America, defend life'.

The President was careful to avoid confrontation with the Pope, whose remarks were a surprise to US officials. They had not expected him to launch into the issue publicly but to raise it during his meeting with the President. Mr Clinton showed no reaction, and later paid tribute to a 'great speech'.

In raising the subject, the Pope, who is on his third trip to the continental US, was on safe ground with many of the 58 million US Catholics. While large numbers differ with the Vatican in other critical areas - including contraception and the ordination of women - several surveys have shown that the majority agree with his views on abortion. But it will have done nothing to narrow the rift between both sides of the abortion debate in the US, which has resulted in deadly violence.

Around half a million people are expected to reach Denver by the time he ends his four-day trip. He has come for World Youth Day, an annual jamboree which some have dubbed the 'Catholic Woodstock'. On Thursday evening, 85,000 rain- soaked young people welcomed the Pope at a stadium, waving white handkerchiefs and stamping their feet. Yesterday he celebrated a mass for US bishops, held in the cathedral where Buffalo Bill was baptised, and was planning to retreat to the Rocky Mountains to hike and rest.

The Catholic Church has never much balked at using its spiritual leader for commercial advantage, but Denver entrepreneurs seem to be breaking new ground. Crowds of youngsters have been spotted wearing life-size foam rubber versions of the papal headgear. 'Popescopes', periscopes for viewing the passing entourage, have been selling well, along with stacks of Pope-adorned souvenirs. There is even a new bumper sticker: 'I partied with the Pope' - unlikely to be spotted on the back of the presidential limo.